Single crystal shape memory alloy devices and methods
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0 Petitions
Accused Products
Abstract
Devices and methods of making devices having one or more components made of single crystal shape memory alloy capable of large recoverable distortions, defined herein as “hyperelastic” SMA. Recoverable Strains are as large as 9 percent, and in special circumstances as large as 22 percent. Hyperelastic SMAs exhibit no creep or gradual change during repeated cycling because there are no crystal boundaries. Hyperelastic properties are inherent in the single crystal as formed: no cold work or special heat treatment is necessary. Alloy components are Cu—Al—X where X may be Ni, Fe, Co, Mn. Single crystals are pulled from melt as in the Stepanov method and quenched by rapid cooling to prevent selective precipitation of individual elemental components. Conventional methods of finishing are used: milling, turning, electro-discharge machining, abrasion. Fields of application include aerospace, military, automotive, medical devices, microelectronics, and consumer products.
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Citations
54 Claims
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7. A guidewire device for use in medical procedures within a body of a human or other animal, the device comprising:
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an elongate guidewire body formed of a single-crystal hyperelastic alloy of copper, aluminum, and a metal selected from the group consisting of Ni, Fe, Co, and Mn having a crystalline phase change transition temperature that is below body temperature, having an austenite crystalline phase at temperatures above the phase change transition temperature and a martensite crystalline phase at temperatures below the phase change transition temperature, so that the elongate body is deformable at a constant force at recoverable strain of at least 9% at body temperature, with a very narrow loading-unloading hysteresis, a recovery which is completely repeatable and complete and a very low yield strength when martensitic, wherein the device is sized for insertion into the body and has an exposed outer surface of single-crystal alloy that is substantially free of micro- or nano-crystals, further wherein the guidewire comprises one portion having a given diameter and an other portion, the other portion having a diameter that is less than the given diameter sufficient to enable the other portion responsive to a given stress to flex through a greater degree than when the one portion is flexed responsive to the given stress. - View Dependent Claims (4, 5, 8, 9, 11, 15, 50)
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16. A method of fabricating a single crystal shape memory alloy having hyperelastic properties, the method comprising the steps of:
- providing a molten melt of a copper aluminum based alloy, pulling a column of the alloy from the melt at a predetermined pulling rate, applying a predetermined hydrostatic pressure on the column and heating the column to a predetermined temperature, the predetermined pulling rate, hydrostatic pressure and temperature being sufficient to crystallize the alloy in the column into a single crystal, and quenching the single crystal.
- View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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53. A guidewire device for use in medical procedures within a body of a human or other animal, the device comprising:
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an elongate guidewire body formed of a single-crystal hyperelastic alloy of copper, aluminum, and a metal selected from the group consisting of Ni, Fe, Co, and Mn having a crystalline phase change transition temperature that is below body temperature, having an austenite crystalline phase at temperatures above the phase change transition temperature and a martensite crystalline phase at temperatures below the phase change transition temperature, so that the elongate body is deformable at a constant force at recoverable strain of at least 9% at body temperature, with a very narrow loading-unloading hysteresis, a recovery which is completely repeatable and complete and a very low yield strength when martensitic, wherein the device is sized for insertion into the body and has an exposed outer surface of single-crystal alloy that is substantially free of micro- or nano-crystals; further wherein the guidewire comprises one portion having a given diameter and an other portion, the other portion having a composition different from the first portion sufficient to enable the other portion responsive to a given stress to flex through a greater degree than when the one portion is flexed responsive to the given stress.
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54. A guidewire device for use in medical procedures within a body of a human or other animal, the device comprising:
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an elongate guidewire body formed of a single-crystal hyperelastic alloy of copper, aluminum, and a metal selected from the group consisting of Ni, Fe, Co, and Mn having a crystalline phase change transition temperature that is below body temperature, having an austenite crystalline phase at temperatures above the phase change transition temperature and a martensite crystalline phase at temperatures below the phase change transition temperature, so that the elongate body is deformable at a constant force at recoverable strain of at least 9% at body temperature, with a very narrow loading-unloading hysteresis, a recovery which is completely repeatable and complete and a very low yield strength when martensitic, wherein the device is sized for insertion into the body and has an exposed outer surface of single-crystal alloy that is substantially free of micro- or nano-crystals; further wherein the guidewire comprises a first region having a transition temperature below 37 degrees C and a second region having a transition temperature above 37 degrees C. - View Dependent Claims (52)
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Specification